Former UFC heavyweight champion Kevin “The Monster” Randleman has passed away at the age of 44.

After rumors began to spread on social media late Thursday, MMAWeekly.com verified with Randleman’s close friend Wes Sims that The Monster had indeed passed away.

Randleman, Sims, and Mark Coleman were the core of the old school Hammer House fight team, but were much more than teammates, they were brothers. Randleman’s family informed Coleman and Sims on Thursday of their brother’s passing. Sims told MMAWeekly.com that an apparent heart attack claimed Randleman.

"It’s true,” Sims told MMAWeekly.com, barely able to speak as his voice was wracked with emotion. “He had a heart attack. I’m floored.”

Randleman’s death came as a shock, as he had just been out and about on the Red Carpet of the World MMA Awards in Las Vegas this past week, where MMAWeekly.com executive editor Scott Petersen interviewed him.

“I can’t believe it. He looked the best I’ve seen him in years,” said Petersen. “He said he was working on a book, like a memoire, but he really lit up talking about how happy he was about his family, particularly his young son.”

Randleman was one of the pioneers of of mixed martial arts, having begun his professional career in 1996. He became the UFC heavyweight champion with a win over Pete Williams at UFC 23. He then spent many years as a staple of the Pride Fighting Championships.

Randleman last fought in 2011, but competed with many of the biggest names in the sport during his decade-and-a-half career. He faced the likes of Fedor Emelianenko, Randy Couture, Mirko “Cro Cop” Filipovic, Chuck Liddell, Quinton “Rampage” Jackson, Bas Rutten, and more.

His death was immediately felt by his fellow fighters, including brother in arms Frank Trigg, who, like Randleman, Coleman, and Sims, transitioned from the world of elite wrestling to mixed martial arts when the sport was in a pivotal transition period.

“I’m not even sure what to say… or do,” Trigg told MMAWeekly.com, clearly rocked by the news. “Such a great competitive spirit inside of an amazing athlete.

sad news, indeed. very young.he was one of the originals, and i will always remember his legendary fights, especially that Fedor slam.cant help but think, though, that his death had something to do with the great amount of steroids he ingested throughout the years.